1. Field of the Invention
This invention relates to a security system, and in particular to an identification badge verification system that detects changes in the reflectivity of a time dependant security or identification badge after a predetermined period of time, e.g., one week, one month, three months, etc.
2. Prior Art
A major problem with temporary identification or security badges is preventing expired, lost and/or uncollected badges from being reused. A known solution to this problem is the use of self expiring badges, i.e., badges that after a period of time indicate thereon that they are expired and that the person does not have access to the secured area. Such time indicators are useful, for example, not only as security badges but also as a means for determining the length of time a perishable item, e.g., food, photographic film, etc., has been on a wholesaler's or retailer's shelf.
Many of these known time indicators, which are generally short term time indicators, are based on the migration of ink from one substrate through another substrate, i.e. in a path perpendicular to the surface of the substrate. After the ink migrates through the substrate(s) it is viewed on a display surface to thereby indicate that the predetermined time has elapsed. Other known time indicators are based on the migration of liquids, jellies or inks through wicks or migration paths to indicate the passage of time. Still other indicators rely primarily upon chemical reactions to cause a visually perceptible change over a desired time period rather than the migration of fluids or compounds.
More specifically:
U.S. Pat. No. 4,212,153 to Kydonieus, et al describes a laminated indicator that changes in a visually perceptible mode with the passage of time. The indicator comprises at least two layers whereby the molecular migration of an agent in an interior layer to the outermost surface of the exterior layer causes a change which is visually perceptible.
U.S. Pat. Nos. 4,432,630, 4,542,982 and 4,779,120 to Haas describe badges with an ambient light sensitive coating thereon which when exposed to ambient light for a specified period of time change to a specified color.
U.S. Pat. No. 4,903,254 to Haas describes a time indicator with a plurality of layers that are adhered together. The indicator has a front part and a rear part. The rear part includes an ink film layer upon a backup layer. At issuance, the front part and rear part are adhered together and the ink migrates from the rear part into the front part.
U.S. Pat. No. 5,058,088 to Haas describes a timing indicator type badge, label or display wherein the relative amount of time that has elapsed from the initial activation of the timing indicator can be easily determined by the progression of a visually perceptible change in color along different areas of the timing indicator. This timing indicator comprises a clear self-adhesive film which is placed over a printed substrate in order to activate the timing indicator. The printed substrate includes a migrating or soluble ink which migrates along the substrate to produce a visual color change.
U.S. Pat. No. 5,107,470 to Pedicano describes a quick acting indicator including a migrating ink that migrates through an opaque layer to display a message. Upon removal of a release paper, a coated indicator portion is brought into contact with a printed base portion, and a printed message migrates through a noncuring layer to display the printed message.
U.S. Pat. No. 5,364,132 Haas et al. describes a reusable self-expiring security identification badge. When the badge is issued, the inked substrate is attached to the base substrate, the inked substrate covering the void indicia area. The overlay substrate is then placed over and attached with the soluble ink of the ink substrate. The ink dissolver of the overlay substrate contacts and co-acts with the soluble ink of the inked substrate to dissolve the ink and allow the ink to migrate through to the overlay substrate to the display surface, where it can be visually perceived, in a preselected time interval.
Applicant has discovered, however, that there are several problems associated with these known time dependant self expiring security or identification badges. In particular, long term, e.g., months, years, etc., identification badges that produce a color change to indicate that a predetermined length time has expired, have the following problems or shortcomings:
1. The diffusion of dye molecules cannot be easily controlled in a step function. PA1 2. Barriers that are made of organic and inorganic (non-metallic) materials are difficult to maintain in a stable condition over months and years, i.e., they have a poor shelf-life. More specifically, the thickness and concentration of the various components is difficult to control over such long periods of time. PA1 3. Organic and inorganic (non-metallic) barriers cannot be produced in very thin layers, e.g., hundreds or tens of thousands of Angstroms.
Additionally, most known security systems that use identification badges rely on a security guard's or receptionist's visual acuity to inspect the badges of people approaching a designated area. This must be done on an individual basis no matter how many people are passing through the area, is inefficient and laborious.
The present invention is designed to compliment the visual acuity of the security personnel with an automatic system that will sound an alarm when an invalid badge has moved into the area monitored. The present invention is particularly useful in high traffic areas such as airports, public and government buildings, such as courts, or other large facilities where many people move through a confined space in rapid succession.
Several additional U.S. Patents could be relevant to the invention herein; in particular: U.S. Pat. No. 4,258,000 to Obermayer; U.S. Pat. No. 4,661,983 to Knop; U.S. Pat. No. 5,095,194 to Barbanell;and U.S. Pat. No. 5,317,987 to Muller et al. In particular:
U.S. Pat. No. 4,258,000 to Obermayer describes a toxic-monitoring material for monitoring of toxic fluids placed in contact with or exposed to the monitoring material. The material comprises a transparent microporous material that has therein a liquid composition that includes a reactant which reacts with the toxic component to change in color or appearance throughout the material.
U.S. Pat. No. 4,661,983 to Knop describes a technique for determining whether an individual item of sheet material is counterfeit. The sheet material incorporates an authenticating material that exhibits a predetermined macroscopic reflectivity characteristic.
U.S. Pat. No. 5,095,194 to Barbanell describes a holographic credit card with an automated verification system.
U.S. Pat. No. 5,317,987 to Muller, et al. discloses an indicator for display of elapsed times consisting of a base to which a chemical substance is applied and a barrier which is fastened to the base to seal the chemical substance to the base. The barrier may have a legible indication such as a letter. A second chemical substance is applied to the top of the barrier and enclosed by a covering foil. Selective pitting of the barrier permits one or both of the chemical substances to penetrate the barrier to uncover the colored base. The barrier may be constructed from commercial aluminized polymer sheet material. The visible change of the barrier in the chemical substances selected may cause a luminescence reaction which may be detected optoelectronically for automated use of the indicator. Other metal layers on epoxide paper, polyester or polyamide film may be used for the barrier.
None of these patents teach or suggest applicants invention and the unexpected benefits derived therefrom.